Conceptual Design of a Vacuum Window at the Exit of the CLIC Post-Collision Line

In this paper, we present a design of the window between the accelerator vacuum and the beam dump at the end of the CLIC post-collision line. We propose to use a thick (1.5 cm) layer of carbon-carbon composite, with a thin (0.2 mm) leak-tight foil. The energy deposition and the temperature increase due to the beam impact, as well as the stress levels in the window, are estimated and we show that Aluminium is the most suitable material for the thin foil. At the beam impact, the temperature increase after the passage of a CLIC bunch train is of the order of 1 K and the subsequent (cyclic) thermal stress remains smaller than 1 MPa. As for the (static) mechanical stress, it is about 4 MPa in the beam impact region, and it goes up to 15 MPa near the lateral edges of the window. Still, these constraints are more relaxed than for the LHC dump window.